"You must never, ever repeat a word from last night," Johnny Carson told Henry Bushkin after sobering up from a barstool confessional. Bushkin gave a lawyerly assurance to "The Tonight Show" host, saying in part, "I would lose my license if during your lifetime I repeated it to a soul."

Maybe Carson's head hurt too much to catch that little caveat. Had he noticed the words "in your lifetime," the entertainer might not have been so keen on hiring a 27-year-old lawyer who likely would outlive him and might one day reveal his personal and professional blemishes.

Is Bushkin's writing about his famously private client an act of betrayal tinged with revenge? Carson did fire him after nearly two decades of devoted service.

Putting that matter aside, few books like "Johnny Carson" have been more engrossing. It's not just a juicy peek inside a celebrity's life from the view of a hanger-on. Bushkin's memoir is also a well-written corporate tale that reveals the tough business of staying America's favorite late-night host, full of stories of money, sex and skullduggery, peppered with plenty of laughs.

Bushkin began handling Carson's affairs in 1970. Carson needed additional legal advice on how to execute a pre-emptive strike on his second wife (there would be two more). Bushkin writes that he proved himself by joining Carson, who was armed with a .38-caliber handgun, and a few others in a raid on the love nest shared by Mrs. Carson and athlete turned sportscaster Frank Gifford. Packing heat didn't protect Carson's emotions: He wept when he realized that he was indeed losing another wife.

Not that Carson had to worry about being lonely - just being careful. Sometime around 1970 his skirt-chasing earned him a beating from a mobster's entourage and a contract on his life. Bushkin says some high-level talks allowed Carson to walk the streets of New York again without fear of being killed for hitting on the wrong guy's girl.

Family and finances were sore spots for Carson. His mercilessly cool mother remained unfazed and unappreciative of his incredible success. He had his own problems relating to his three boys. When son Rick landed in a mental hospital for two weeks, Bushkin writes, Carson refused to drive across town to visit. Pleading that the publicity would not be good for either Carson, he sent Bushkin instead.

In Bushkin's telling, Carson was too trusting of managers and other financial advisers, making him an easy victim of bad deals. He had other weaknesses, too. Mrs. Carson 3.0 was willing to sign a prenuptial agreement designed to protect Carson's fortune. But he balked at the last minute, saying it was a terrible way to start a marriage. "This romantic gesture," his lawyer says, "would cost Johnny $35 million."

Bushkin's memoir adds shading and detail to the portrait of Carson already established. The master of the talk-show medium was often uncomfortable with individuals. In the right mood, he could be witty, generous and fun to be around - and, in a flash, turn cruel and cold. Late-night TV's naughty Midwesterner was also a roving husband, unpredictable when drunk, a four-pack-a-day smoker prone to obscenity-laden rants. When he drove a car he usually carried a handgun for protection, the book says.

Carson fired Bushkin over a business matter, the lawyer says, and litigation ensued. All these years later Bushkin seems torn between reveling in their friendship and taking an opportunity to get even. He tries to absolve himself of wielding a literary dagger by imagining that Carson, who he says was suspicious of flattery and sentimentality, would have been happy with this book because it's accurate.

Imagine instead that self-serving statement in the hands of one of Carson's late-night characters, Carnac the Magnificent. The envelope he tears open might well reveal this answer: "Fat chance."

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Douglass K. Daniel is the author of "Tough as Nails: The Life and Films of Richard Brooks" (University of Wisconsin Press).